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SATRAN - Satellite Tracking Antenna

3D-printed, wifi-enabled and android controlled antenna rotator.

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A compact satellite antenna azimuth/elevation rotator with android app. Available from my website as an affordable kit, but it's also possible to 3D-print most parts yourself!

This is a continuation of an old project of mine, when I built a simple satellite antenna tracker with an android app that calculates the position of any satellite using its "kepler elements", and controlling the Az-El antenna rotator to track it across the sky. During a few late nights together with two other ham operators, we built a crappy but functional prototype from spare parts. Now some years later, I decided to redesign it from the ground up as an affordable and easy to use kit.

Controller

The onboard microprocessor is an ESP8266 NodeMCU board with wifi-capability that can be controlled manually in a web-interface or automatically through an android app.

Motion happens with the help of two Nema17 stepper motors, and the rotator has a platform that allows for many different kinds of antennas or a small satellite dish.

Now available from my website!

Kits are soon back in stock on my website and the open source STL-files for 3D-printing are also available there for download.

If you have any request or feedback, please let me know! 

/  Daniel  www.satran.io

  • Milling some MDF

    Daniel Nikolajsen06/08/2021 at 12:07 0 comments

    Yup, aluminum was a bit too tough for my benchtop CNC. So I found a supplier of tooling board that I hope to try out soon, they promised to send me some samples. Tooling board is a high density polyurethane block that you can easily machine and hopefully use to make injection molds. 

    But, it is quite expensive.

    Thats why today, I tested out the CNC gcode with a piece of MDF wood board. It worked quite good in the beginning, but when I got to some depth the thinner details snapped right off. Hopefully tooling board wont have this issue, or I will need to replace all the smaller details with metal pins which would be very time consuming.

    But in total, I'm quite happy with the experiment. Slab some sealer on the mold and I can use it to try the injection molding machine. If it works and the entire mold gets filled up with plastic, I will know if I can use some sort of polymer molds instead of aluminum. If not, I probably need to spend a few thousand dollars on contracting someone to make the molds. 

  • Plastic fantastic

    Daniel Nikolajsen06/06/2021 at 15:05 0 comments

    For the second attempt with the injection molding machine I went to our old farmhouse in the woods. No neighbors to disturb if the contraption starts bellowing out smoke like the last time.

    But it didnt! It actually worked quite good this time, even if some improvements are needed for it to be truly usable. All in all, not too bad for a machine that only cost me around 400 USD.

    It will probably suffice to insulate the nozzle, preheat the aluminium mold plus redesign it with a slightly bigger inlet. Because the melted plastic solidified way to quick and didnt get very far into the mold as you can see...

    And of course this is not one of the final molds, but just an early attempt at milling aluminium in my benchtop CNC.

    Slow but steady. Build, measure, learn! 

  • Glorified smoke machine

    Daniel Nikolajsen06/03/2021 at 12:10 0 comments

    Today was the day I fired up the injection molding machine for the first time. Literally, "fired up". It worked like a charm the first few minutes, but then in an instant it smoldered nasty white smoke all over the apartment. Thank god for emergency stop buttons.

    After some guessing, I found out a few errors to fix. First I need to adjust the PID thermocontrollers to have a slower cycling of the heaters, plus relocate the thermocouplers ("sensors") closer to the actual heaters for a faster response.

    The main fault was that one thermocoupler was mounted directly to the nozzle block, which because of its size and mass heats up a lot slower than the actual barrel inside the heater element. Therefore the plastic closest to the heater probably goes up to over 250 degrees celsius (500 fahrenheit) before the nozzle even have reached 150. 

    Some insulation around the nozzle is also probably a good idea. 

    Plus, next time I will definitely bring the whole setup outside =) 

  • Improvements to the app

    Daniel Nikolajsen06/03/2021 at 05:10 0 comments

    The list is long of all the todos, but yesterday I finally got the new app improvements working. Automatic kepler retrieval from Celestrak, with a search functionality. Now you always have the latest TLEs ("coordinates") in your app, plus you can easily swap between sats.

    But there's a lot more coming. I am making a world map that shows where the satellite is, plus a manual rotator control, plus automatic IP search, automatic GPS position retrieval, remove the need for restarts between sat changes etc etc etc

  • Spring is in the... machine

    Daniel Nikolajsen05/28/2021 at 09:09 0 comments

    Today I built the last remaining part for the injection molding machine; a spring mount for the actual barrel that will contain the melted plastic. With this, you can put your mold a few millimeters under the nozzle and when pressure is applied from above, it gets pushed down against the mold, giving a decent seal. 

    But now its time for coffee to get some energy back. Unfortunately I experienced a nasty customer trolling and threatening me despite me being friendly, trying to solve the issue and even issued a refund. But thats the downside of doing business, sometimes you have to deal with some rotten eggs. Telling from some forum threads, its apparently not his first time making trouble. Thankfully the mails I get once a week or so from customers praising me for my great customer support and innovative product is what gets me up in the morning. Thank you, and keep em coming!

  • One more day

    Daniel Nikolajsen05/27/2021 at 17:33 0 comments

    Yup, tomorrow is probably the day when I finish the injection molding machine. It's been a great run, but soon it is time to see if it will work as intended. At least the electronics are working now, with double thermostats and (at least for my small workshop) a massive hydraulic setup. *fingers crossed*

  • First try at milling aluminium molds

    Daniel Nikolajsen05/25/2021 at 06:59 0 comments

    For the injection molding to work, I need to have molds. Yesterday I started with my first ever try at milling aluminum in my homebuilt CNC-machine. It started off quite okay, but then suddenly the z-axis dropped and buried its nose deep in the aluminium stock. The code and everything seems okay, so I am wondering if it was the stepper motor going crazy thanks to excessive heat. 

    Today I have put a heatsink and a fan on the motor, hopefully that will do the trick. Otherwise my next experiment will be to make molds in a somewhat softer material like polyurethane or polyester, because aluminium is both tricky, hard and expensive.

  • Finished the instructions

    Daniel Nikolajsen05/21/2021 at 12:10 0 comments

    Today I got time to finish the assembly instructions, which required a lot of pictures. But now it's as good as it needs to be, for everyone to be able to put together their kit. And together with the video, I would be very surprised if anyone managed to mess up their build =)

    The full instructions can be found at www.satran.io/downloads

  • Assembly instructions deluxe

    Daniel Nikolajsen05/11/2021 at 09:53 0 comments

    The assembly instructions for the satellite rotator has been sparse, since I made a video I assumed that would be enough. But it seems some prefer the printed version, so today I started a much more detailed manual with a photo for every step. Ingvar Kamprad would have been proud... (for those who arent Swedes, he's the founder of IKEA)

  • Its all in the fine... parts

    Daniel Nikolajsen05/10/2021 at 08:58 0 comments

    Welding together the big frame for the injection molding machine was the easy part. Now comes all the small stuff that takes up all the time, but makes all the difference. Todays mission is to make holders for the temperature sensors which will give a good connection against the circular cylinder where all the melted plastic goes. It's the aluminium block you see in the lower right...

    Also the brass end plug needs to be transformed into a makeshift nozzle, which is why Im taking a trip later this week to my metal shop out in the woods. The nozzles need to be machined nicely and get a hole drilled through the middle in a perfectly sized diameter (that I have no clue about). I think I'll start with 3mm.

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Discussions

ahsima1 wrote 02/26/2021 at 18:06 point

Hi!

The STL files for the "Top plate" and "Turret base" seem to be different from the pictures. Looks like they lack the groves for ball bearings. Can you confirm those are indeed the right files, or if they aren't, upload the right files.
Thanks!

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/28/2021 at 09:22 point

They are the right ones. the BOM was an old one but is updated now. The continuous ball bearing grooves didnt work, the balls stacked up against each other and made too much friction. In the current version there are only 8 balls on each layer, evenly spaced.

  Are you sure? yes | no

Mihai S wrote 02/12/2021 at 19:25 point

HI, for the past 3 weeks I've been printing like crazy different rotors projects, I like your project but where is the firmware? github?

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/12/2021 at 20:15 point

Shop will open in approx a week where you can buy control board with firmware preinstalled (EU customers only, exports will begin in about a month)

  Are you sure? yes | no

k.jurczok wrote 02/05/2021 at 09:15 point

good luck with adversity. I believe that the failure will be managed quickly :)

  Are you sure? yes | no

k.jurczok wrote 02/01/2021 at 09:57 point

Hi!

What is maximum load of this rotor?

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/17/2021 at 06:43 point

It's built for smaller antennas, the exact weight limit is still to be tested.

  Are you sure? yes | no

jed wrote 01/27/2021 at 15:47 point

Perhaps you understand this, but your 10 ohm steppers take a higher voltage to get to 1A. The A4988 driver carriers that look like what you are using are good for up to 35V and more voltage equates to quicker ramp time to the correct current. Your 9V is near the 8V MINIMUM for these drivers. Also, remember you can only measure stepper current when they are HOLDING and not turning. If you'd rather use 10 ohm steppers, try 24V.

What a great project! Best of luck!

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/27/2021 at 16:07 point

Exactly I didnt realise first that it was 10ohm motors I had. Since the entire board needs to run on a single power supply it needs to be at 8-10 volt because of the NodeMCU and A4988. Otherwise the controller board needs to be redesigned with extra voltage control, and because of the cramped space in the housing the entire hardware probably would need to be redesigned too. Thx!

  Are you sure? yes | no

Thomas Daniels wrote 01/18/2021 at 16:38 point

Hi, this looks very interesting and affordable. I have a few questions: Will this rotator be strong enough to carry a 2m and a 70 cm XYagi, each about 1,5m long? Is it watertight enough for permanent assembly outside? Can it be controlled by connecting to an IP-address using any browser? (I do not have any androids here). And how much will it be? If I understand correctly, you are still in the development process?

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/22/2021 at 06:17 point

Hi, a double antenna system with such large arrays I think should be too much for this design unfortunately. Also it is not completely weathertight and durable enough to withstand hard wind, so not recommended for prolonged outdoor use.

 But if I get enough response I hope to make a better version (but more expensive) later on made from aluminium, stronger motors etc. The first version thats still in development is made to be a cheap and simple, costing from around 60USD for only the controller board up to perhaps up to 230 USD for a full kit. The first will probably be available for sale early february. 

It can be controlled via IP/browser but since the positioning (calculating the direction) is done in the app, you need some other software to know where to point the rotator. Perhaps Gpredict (win) and others could work.

  Are you sure? yes | no

jcwren wrote 01/18/2021 at 00:15 point

It's an interesting rotator design and is nice and compact. My concern is the amount of load you're putting on the gear train as the antenna changes azimuth. If the antenna is balanced and the antenna is pointing at the horizon, there's no stress. But as the azimuth increases, the load dramatically increases as it's not balanced on the pivot point as it is with a conventional antenna rotator. When the azimuth is 90 degrees, the gear train is supporting the full weight of the antenna and it's increased because it's cantilevered. What are your thoughts about that?

  Are you sure? yes | no

Daniel Nikolajsen wrote 01/18/2021 at 05:39 point

That's correct, it's not perfectly balanced. But the design isn't made for use with any large 2meter yagi antennas that weigh many kilograms, but for smaller types perhaps a 70cm yagi or some compact LPDA type.

Also when the antenna is in zenith (pointing straight up), the entire antenna is offset from the axle but only with a few inches. This means that the torque on the elevation worm gear is actually not that large.

But changing the axle (M8 threaded rod) to a longer one and putting a mount directly on the axle shouldnt be a problem either if you prefer that approach instead. That should also be preferred if you want to have two antennas - one on each side.

  Are you sure? yes | no

Tom wrote 02/03/2021 at 21:31 point

I can't see it struggling to drive something like this: 

http://www.schnizer.com/SOTAblog/equipment/lightweight-2m-yagi-sota/

  Are you sure? yes | no

Daniel Nikolajsen wrote 02/09/2021 at 08:02 point

No Tom, that yagi shouldnt be any problem, also in my video (and on all the boards I'll ship) the stepper drivers are only tuned to around half capacity to be sure not to overheat anything. With tweaking you could probably more than double the torque without any issues.

  Are you sure? yes | no

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